This application hereby incorporates each of the provisional applications, as listed on the Application Data Sheet that is associated with the subject application, by reference and in their entireties, including any figures, tables, chemical formulas, and/or drawings.
There are numerous processes responsible for the modulation of visible light. Among them, electrochromic techniques can use the reversible change of color and/or optical density obtained by an electrochemical redox process in which the oxidized and the reduced forms have different colors, indices of refraction, or optical densities. These techniques are readily employed in a multitude of applications such as display panels (1), camouflage materials (2), variable reflectance mirrors (3), variable optical attenuators and variable transmittance windows (4, 5, 6). For example, the Gentex electrochromic mirror system has been successfully commercialized in the automotive industry.
Electrochromic devices (ECDs) based on inorganic semiconductors have a long history, and their performance has improved steadily since their creation (7). When viewed in this context, the recent rapid progress made with organic conducting and electroactive polymers in a variety of fields suggests they may find numerous practical applications in the near term (8). These materials have made valuable contributions to the emerging fields of electrochromic devices (4), as well as organic light emitting diodes (9, 10) and photovoltaics (11). In terms of electrochromics, the remarkable advances in their performance can be viewed from several fronts. First, the range of colors now available effectively spans the entire visible spectrum (12) and also extends through the microwave, near-infrared and mid-infrared regions. This is due to the ability to synthesize a wide variety of polymers with varied degrees of electron-rich character and conjugation. For example, a fine adjustment of the band gap, and consequently of the color, is possible through modification of the structure of the polymer via monomer functionalization (13), copolymerization (14), and the use of blends, laminates and composites (15, 16). Second has been the marked increase in device lifetimes. The key to this is control of the degradation processes within the polymeric materials (by lowering the occurrence of structural defects during polymerization) and the redox system (17, 18). Third, the polymer based ECDs have achieved extremely fast switching times (milliseconds) for large changes in optical density. This fast switching is attributed to a highly open morphology of electroactive films, which allows for fast dopant ion transport (19). Other beneficial properties of polymers are outstanding coloration efficiencies (20) along with their general proccessability.